The invention relates to a control and testing system for an installation using a multiplicity of contactor apparatus each comprising power switches which are actuated by an electromagnet having an energization coil whose accessible terminals are connected electrically to a supply and processing circuit capable of amplifying, respectively delivering or interrupting, automatically or manually, current signals having appearance or disappearance delays with respect to reference signals or not.
Known control systems of the prior art generally comprise a cabinet or board in which are disposed circuits for processing different information which may comprise programmable automatic devices, timers, function selectors, signalling lamps, as well as manual control means, independent of the automatic device, for carrying out adjustments for example.
In one embodiment, also widely used, some of these means are disposed in reduced number, not on the panel of a cabinet, but on the front face of the cover of a small box containing the said contactor(s) to which they are connected by conductors going either from the cover to the terminals of the contactor coils or extending directly between some of these means and the said terminals when these members are all fixed to the base of the box.
A determined number of simple functions whose execution is left usually to an automatic device assembly, when the final structure of the latter has been worked out beforehand, may nevertheless subsequently become necessary. This case occurs in installations where progressive evolution implies a corresponding increase in the number of functions related for example to new regulations, such as those concerning safety, or those which are imposed when new manufacturing units are added to the original units.
In this latter case, the size of a cabinet or respectively a box may be insufficient.